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Recombination between heterologous human acrocentric chromosomes
Andrea Guarracino1,2, Silvia Buonaiuto3, Leonardo Gomes de Lima4
1Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, TN, USA.
Nature
|May 10, 2023
Summary
Human acrocentric chromosomes contain pseudo-homologous regions (PHRs) that indicate recombination between non-homologous sequences. These regions explain recurrent Robertsonian translocations, confirming long-standing cytogenetic hypotheses.
Area of Science:
- Genomics
- Human Genetics
- Molecular Biology
Background:
- Short arms of human acrocentric chromosomes (SAACs) exhibit homology, including ribosomal DNA and segmental duplications.
- Previous genome assemblies offered limited insight into whether homology patterns were ancestral or maintained by recombination.
Purpose of the Study:
- To investigate the nature of homology in SAACs and its role in chromosomal rearrangements.
- To determine if recombination occurs between non-homologous acrocentric chromosome sequences.
Main Methods:
- Utilized an all-to-all comparison of the Human Pangenome Reference Consortium (HPRC) dataset.
- Constructed a variation graph from centromere-spanning acrocentric contigs.
- Analyzed linkage disequilibrium decay in pseudo-homologous regions (PHRs).
Main Results:
- Identified PHRs within acrocentric chromosomes, suggesting recombination between non-homologous sequences.
- Observed nearly identical contigs between heterologous acrocentric chromosomes in T2T-CHM13 assembly.
- Found faster decay of linkage disequilibrium in PHRs, indicating higher recombination rates, except on chromosome 15.
Conclusions:
- PHRs provide sequence and population-based evidence for recurrent Robertsonian translocations.
- The arrangement of PHRs supports crossover within inverted duplications, explaining translocation breakpoints.
- Findings confirm hypotheses on the basis of Robertsonian translocations developed from cytogenetic studies.
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